Sound-proofing materials and sound-absorbing materials are used in various settings to suppress noise. For example, dashboard insulators and floor insulators can be used as sound-absorbing and sound-proofing materials for automobile interiors to suppress engine room noise or suppress noise entering from outside the vehicle. In some existing systems, felt and other types of non-woven fabrics or moldable porous resins (e.g., composed of urethane foam) are used for these sound-absorbing materials due to their low cost. In addition, in some existing systems, required levels of sound-absorbing performance are obtained by increasing the thickness of these materials to enhance noise absorbing effects.
Patent Document 1 (Published Japanese Translation No. 2002-505209 of PCT International Publication No. WO 99/44817) describes a structure in which a second fiber layer composed of melt blown microfibers is laminated onto a first fiber layer composed of a non-woven fabric or plastic foam.
Patent Document 2 (Japanese Patent Application Laid-open No. 2003-49351) describes an automotive sound-absorbing material in which a melt blown, microfine fiber non-woven fabric is laminated onto one side of a polyester fiber non-woven fabric.